A Terran Empire captain loyal to Emperor Georgiou who relishes torturing the captured Gabriel Lorca in an agoniser booth aboard the ISS Charon, in revenge for the fate of his sister Ava.
Captain Maddox appears in Vaulting Ambition, played by Dwain Murphy. When Burnham delivers Lorca to the Emperor's palace ship as a prisoner, Maddox takes charge of him.
He blames Lorca for seducing and then discarding his sister, and makes him repeat her name between sessions in the booth. Lorca endures it, since being brought aboard the Charon was his aim all along.
At the end of the episode Lorca tricks a guard, frees himself and kills Maddox, remarking coldly that he had liked Ava well enough until someone better came along. The scene confirms for the audience that Lorca is himself a Terran.